Thin film transistor-liquid crystal display (TFT-LCD) is known as the display required for the high pixel density and quality. In general, the TFT-LCD includes a bottom plate formed with thin film transistors and pixel electrodes and a top plate formed with color filters. The liquid crystal is filled between the top plate and the bottom plate. In each unit pixel, a capacitor and a further capacitor are provided which are formed by virtue of the TFT serving as the switching element of the unit pixel. In the operation, a gate signal voltage is applied to the TFT that is the switching element of each unit pixel. The TFT receives the gate signal voltage, it is turn on so that data voltage carrying image information can be applied to the corresponding pixel electrode and the liquid crystal via the TFT. When the data voltage is applied to the TFT, the arrangement of the liquid crystal moleculers is change, thereby changing the optical properties and displaying the image.
A color filter (CF) plate is used in the LCD to show the colored portion of the screen. In general, the viewing angle and the color performance are affected by the design of the color filter. Multi-gap structure is widely used to making the color filter plate for LCD and it has been applied in TN (TFT) and OCB (optical compensation bend) mode. FIG. 1 shows a conventional multi-gap LCD. In the structure, red, blue and green pixels are respectively formed on a glass 2. A first photoresist 4 is formed on the green and the blue pixels. Further, a second photoresist 6 is only formed on the top of the blue pixel. Between the glass 2 and a further glass 8 is liquid crystal 10. Thus, the gap spacing dR, dG and dB are difference. Namely, the color filter plate has a multi-gap structure.
Typically, .DELTA. nd/.lambda. is designed to minimize or maximize the transmission, wherein the n is the integer number, the d is the gap spacing between the glass 8 and the color pixels, .lambda. indicates the wavelength of light. Thus, the red pixel has the largest .DELTA. nd, and the blue pixel has the smallest .DELTA. nd in the three color pixels. The object of the multi-gap structure is to keep the constant .DELTA. nd/.lambda. value. However, the proces for forming above structure needs at least two photoresist coating and two patterning steps.